Motor control device and motor control method

Abstract

A motor control device includes processing circuitry configured to calculate a current command value corresponding to torque that should be generated by a motor, divide the calculated current command value into individual current command values for coil groups, control power feeding to the coil groups independently for each of the coil groups based on a corresponding one of the individual current command values, set, for each one of the coil groups, an upper limit value of a corresponding one of the individual current command values and, when the individual current command value for any one of the coil groups is limited to a value that is smaller than a corresponding one of the upper limit values, supplement an amount limited in the individual current command value by increasing the individual current command value for at least a remaining one of the coil groups.

The invention claimed is: 
     
       1. A motor control device that controls a motor including coil groups, the motor control device comprising processing circuitry, wherein
 the processing circuitry is configured to: 
 calculate a current command value corresponding to torque that should be generated by the motor; 
 divide the calculated current command value into individual current command values for the coil groups; 
 control power feeding to the coil groups independently for each of the coil groups based on a corresponding one of the individual current command values; 
 set, for each one of the coil groups, an upper limit value of a corresponding one of the individual current command values; and 
 in response to the individual current command value for a first coil group of the coil groups being limited by a limit amount to a value that is smaller than a corresponding one of the upper limit values, increase the individual current command value for at least a second coil group of the coil groups by the limit amount. 
 
     
     
       2. The motor control device according to  claim 1 , wherein the processing circuitry is configured such that (a) the individual current command values for the coil groups are unevenly divided, and (b) in response to the individual current command value for the first coil group being limited by the limit amount to the value that is smaller than the corresponding one of the upper limit values, the processing circuitry increases the individual current command value for at least the second coil group of the coil groups by the limit amount. 
     
     
       3. The motor control device according to  claim 1 , wherein the processing circuitry is configured such that (a) the individual current command values for the coil groups are evenly divided, and (b) in response to the individual current command value for the first coil group being limited by the limit amount to the value that is smaller than the corresponding one of the upper limit values, the processing circuitry increases the individual current command value for at least the second coil group of the coil groups by the limit amount. 
     
     
       4. The motor control device according to  claim 1 , wherein the processing circuitry is configured to:
 calculate the limit amount for each of the coil groups, the limit amount being a difference between (i) the individual current command value prior to being limited for each of the coil groups and (ii) an actual value of current supplied to each of the coil groups; and 
 add the limit amount calculated for each of the coil groups having a limit amount greater than zero to the individual current command value of at least another one of the coil groups. 
 
     
     
       5. The motor control device according to  claim 1 , wherein the upper limit values of the individual current command values for the coil groups are each set to a value that is obtained by equally dividing, by the number of the coil groups, the current command value corresponding to a maximum torque that can be generated by the motor. 
     
     
       6. The motor control device according to  claim 1 , wherein the processing circuitry includes the same number of individual controllers as the number of the coil groups, the individual controllers being configured to control power feeding to the coil groups independently for each of the coil groups. 
     
     
       7. The motor control device according to  claim 1 , wherein
 the motor is configured to generate torque given to a steering mechanism for a vehicle, and 
 the processing circuitry is configured to calculate the current command value based on a steering torque. 
 
     
     
       8. A motor control method for controlling a motor including coil groups, the motor control method comprising:
 calculating a current command value corresponding to torque that should be generated by the motor; 
 dividing the calculated current command value into individual current command values for the coil groups; 
 controlling power feeding to the coil groups independently for each of the coil groups based on a corresponding one of the individual current command values; 
 setting, for each one of the coil groups, an upper limit value of a corresponding one of the individual current command values; and 
 in response to the individual current command value for a first coil group of the coil groups being limited by a limit amount to a value that is smaller than a corresponding one of the upper limit values, increasing the individual current command value for at least a second coil group of the coil groups by the limit amount.